Vol 70, No 2 (2011)
Original article
Published online: 2011-06-01
Median aperture of the fourth ventricle revisited
Folia Morphol 2011;70(2):84-90.
Abstract
Background: The median aperture of Magendie is the largest of three openings
of the fourth ventricle and thus it forms the main path for the outflow of
the cerebrospinal fluid from the ventricle. The Magendie aperture connects the
fourth ventricle with the cisterna magna and makes a natural corridor for neurosurgical
approach and inspection of the ventricle and its floor. The purpose
of this study was to give a contemporary anatomical view of this structure in
the context of historical data.
Material and methods: The Magendie foramen was studied in 30 fixed specimens of human brainstems with cerebella. The microdissection technique was used. Measurements were taken with a microscope ocular ruler.
Results: The aperture is limited by the following structures: obex and gracile tubercles inferiorly, and tela choroidea with choroid plexus superolaterally. Obex tubercles usually have the form of a piece of neural tissue bridging two halves of the brainstem above the entrance to the central canal. Gracile tubercles together are 8.15 mm wide and the maximal width of the foramen is 6.53 mm. Tela choroidea attaches laterally at both sides to the inferior medullary velum. In most cases the right and left choroid plexus are connected to each other with a triangular membrane of tela choroidea, which protrudes through the median foramen and attaches to the vermis at a highly variable level.
Conclusions: We hope that the presented description of anatomical relations around the Magendie aperture, with its new measurements, will be helpful for those operating in the area and will explain some of the inaccuracies found in literature. (Folia Morphol 2011; 70, 2: 84–90)
Material and methods: The Magendie foramen was studied in 30 fixed specimens of human brainstems with cerebella. The microdissection technique was used. Measurements were taken with a microscope ocular ruler.
Results: The aperture is limited by the following structures: obex and gracile tubercles inferiorly, and tela choroidea with choroid plexus superolaterally. Obex tubercles usually have the form of a piece of neural tissue bridging two halves of the brainstem above the entrance to the central canal. Gracile tubercles together are 8.15 mm wide and the maximal width of the foramen is 6.53 mm. Tela choroidea attaches laterally at both sides to the inferior medullary velum. In most cases the right and left choroid plexus are connected to each other with a triangular membrane of tela choroidea, which protrudes through the median foramen and attaches to the vermis at a highly variable level.
Conclusions: We hope that the presented description of anatomical relations around the Magendie aperture, with its new measurements, will be helpful for those operating in the area and will explain some of the inaccuracies found in literature. (Folia Morphol 2011; 70, 2: 84–90)
Keywords: anatomychoroid plexuscisterna magnaforamen of Magendieneurosurgical approach
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